1. Field
The present disclosure relates to a method of manufacturing a phase-change random access memory using laser interference lithography, and more particularly, to a method of manufacturing a phase-change random access memory capable of forming a nanoscale pattern over a large area using laser interference lithography.
2. Description of the Related Art
A phase-change random access memory (PRAM) is the next-generation memory semiconductor which stores data by determining a phase change in a particular material. The phase-change random access memory has advantages of both a flash memory in which stored information is not erased even though power is turned off and a dynamic random-access memory (DRAM) which has a high processing speed.
The phase-change random access memory includes phase change materials representing two or more different states, and the states of the phase change materials include amorphous and crystalline states. Generally, the crystalline state has an ordered lattice structure while the amorphous state has a disordered structure. These two crystalline states have different resistances, and a phase change occurs in response to a temperature change. Therefore, the phase change may be used to store data bits.
In order to minimize the amount of voltage used in a cell of the phase-change random access memory, the cross-section of the path of a current passing through the phase change material has to be minimized. Therefore, in a case of a memory array having a plurality of memory cells, a patterning technique capable of implementing fine line widths on the order of nanometers is required.
As a method of implementing fine line widths on the order of nanometers, electron beam lithography, focused ion beam lithography, nanoimprint lithography, and the like are used.
However, in the case of the electron beam lithography and focused ion beam lithography processes, although ultrafine patterns are able to be implemented, there is a difficulty in implementing a memory array structure having a plurality of cells over a large area.
In addition, in the case of the nanoimprint lithography process, additionally required stamps are typically manufactured by the electron beam lithography, and thus there is a problem in that great manufacturing cost and time is consumed. In addition, in the case of the nanoimprint lithography process, residual layers are generated after imprinting, and thus there is a problem in that an additional etching process for removing the layers is needed.